Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/12—Mountings, e.g. non-detachable insulating substrates
  • H01L23/14—Mountings, e.g. non-detachable insulating substrates characterised by the material or its electrical properties
  • H01L23/15—Ceramic or glass substrates
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
  • H01L21/4803—Insulating or insulated parts, e.g. mountings, containers, diamond heatsinks
  • H01L21/4807—Ceramic parts
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/30—Technical effects
  • H01L2924/301—Electrical effects
  • H01L2924/3011—Impedance
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/02—Details
  • H05K1/03—Use of materials for the substrate
  • H05K1/0306—Inorganic insulating substrates, e.g. ceramic, glass
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent

Definitions

• This invention relates to a substrate for electronic circuits which operate in the microwave frequency range, such as hybrid circuits.
• the invention is also concerned with a method for making such a substrate.
• quartz which is subject however, to two types of defects:
• quartz has thermal characteristics which make it sensitive to thermal shock
• quartz has a very low coefficient of linear expansion in comparison with other materials which are used in that technology, thus making it very difficult and even impossible to use it in some cases;
• quartz has very low heat conductivity in comparison with that of other materials like beryllium oxide or alumina.
• boron nitride is advantageous for the following reasons:
• boron nitride plates of large size can be sintered, thus making it possible to form substrates having dimensions, for example, of 300 ⁇ 125 mm across the sides, which is impossible in the case of quartz;
• boron nitride cannot be metallized by conventional means such as thick-film deposits (silver, palladium silver, or platinum and so on), thin films deposited in vacuum or by chemical process. Boron nitride is in fact too soft at the surface and too friable. The cohesion of the grains at the surface of a boron nitride plate is insufficient and is comparable to that of a plaster surface, for example.
• An object of the invention is to make it possible to use boron nitride as a metallized substrate.
• An other object of the invention is to endow the boron nitride with a hard and non-friable surface by depositing a material to a given thickness, for example of the order of 10 to 15 microns, which ensures cohesion of the grains without impairing the electric and thermal characteristics of the boron nitride.
• a glass which is chosen so as to have a dielectric constant ⁇ in the vicinity of the one of boron nitride and having a suitable coefficient of expansion is wholly satisfactory for this purpose.
• the glazed surface can then be metallized by conventional means.
• a substrate for a microwave circuit comprising a plate comprising boron nitride having two large faces, and a glass film deposited at least on one of said faces, thereby permitting surface metallization of said face and ensuring cohesion of the grains of boron nitride.
• the type corresponding to a composition containing approximately 42% boron, 53.5% nitrogen, and different impurities including 1.5 to 2.5% oxygen and 1.5% calcium has the following characteristics when it is sintered in the form of plates:
• thermal conductivity 0.15 cal/cm 2 /sec/°C./cm.
• boron nitride is advantageous for the formation of substrates although its dielectric constant of 4.11 is slightly greater than that of quartz which is equal to 3.7. As stated earlier, however, boron nitride is too soft and too friable at the surface to ensure perfect adhesion of a metallization deposit.
• the thermal and dielectric characteristics of a material of this type are not impaired but, on the contrary, its surface is made hard and non-friable by depositing a film-layer of glass chosen from glasses having a dielectric constant in the vicinity of the one of the quartz or the boron nitride.
• the glass chosen becomes more similar to pure silica SiO 2 as the requisite characteristics for operation at microwave frequencies are more stringent.
• a practically pure silica, of high microwave quality has a melting point in the vicinity of 1300° C.
• a lightly doped glass having a melting temperature of the order of 700° C.
• the glass which is chosen can be deposited in film-layers having a thickness of the order of only 10 to 15 microns by screen-process deposition of a conventional paste containing glass powder, binders and organic agents. This layer is then fired in a furnace at a temperature which is at least equal to the melting point of glass, and at which all the organic solvents are evaporated.
• the glass can also be deposited by radiofrequency cathodic sputtering in vacuum in accordance with the so-called thin-film technology, or else by chemical deposition in vapor phase at low pressures in accordance with the technology known as chemical vapor deposition (CVD).
• the glass chosen for forming either a thin film or a layer of greater thickness of the order of 10 to 15 microns permits good cohesion of the boron nitride grains at the surface, thereby resulting in surface glazing or vitrification.
• the glass layer can be metallized in accordance with the thin-film technique, which means that the surface of the boron nitride substrate then has the ability to withstand the passing of the metallization screens during the screen-process deposition. By reason of its very small thickness, the glass layer does not carry any appreciable penalty in regard to thermal resistance of the functional device.
• the glass layer can be chosen so as to ensure that its coefficient of linear expansion is very close to that of the boron, thus preventing any subsequent breakaway or delaminations between the boron nitride layer and the glass layer during operation.
• ⁇ and tg ⁇ it is possible to adapt them to those of boron nitride according to the nature of the doping elements added to the glass. The result thereby achieved is that there is no dielectric discontinuity within the boron nitride substrate which is thus improved by the addition of a glass layer at the surface.
• the invention has been described in the foregoing on the basis of a non-limitative example of a substrate having large dimensions, that is to say dimensions which cannot be attained in the case of a quartz substrate.
• the full value of the present invention remains unaffected if it is applied to a substrate having smaller dimensions down to what is conventionally designated as an insulating block of about the same size as a semiconductor chip, the block being located and bonded between the microwave semiconductor chip and an encapsulation housing.
• a substrate of this type can now be metallized makes it possible either to form metallized terminations for bonding semiconductor chips or to deposit conductive strips on said substrate in order to fabricate circuits which operate in the microwave frequency range in accordance with the so-called strip-line technology.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Ceramic Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Inorganic Insulating Materials (AREA)
• Laminated Bodies (AREA)
• Insulating Bodies (AREA)
• Waveguides (AREA)
• Glass Compositions (AREA)
• Ceramic Products (AREA)

Applications Claiming Priority (2)

Publications (1)

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Cited By (5)

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Citations (4)

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• 1982
  • 1982-04-16 FR FR8206599A patent/FR2525391B1/fr not_active Expired
• 1983
  • 1983-04-14 US US06/484,994 patent/US4440828A/en not_active Expired - Fee Related
  • 1983-04-15 DE DE8383400752T patent/DE3363722D1/de not_active Expired
  • 1983-04-15 EP EP83400752A patent/EP0093633B1/fr not_active Expired
  • 1983-04-16 JP JP58066346A patent/JPS58212940A/ja active Granted

Patent Citations (4)

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